Carmelo Anthony’s bad back responded well the day after he made his return to the Knicks lineup.

The Knicks star scored 31 points in 41 minutes in Sunday night’s 86-79 loss to the Heat at the Garden after missing the previous two games on the road against the Mavericks and Thunder, and though he didn’t practice fully on Monday as part of a recovery day, he did take jump shots after the Knicks’ workout.

“I feel all right for the most part, just some ordinary soreness after a game, nothing major,” said Anthony, who left in the first half of a loss to the Rockets in Houston Nov. 24 because of painful back spasms. “I feel good about that.

“I think it’s a matter of me not even kind of thinking about that once I get into the flow of the game, kind of taking my mind off of it, seeing early what I can take.”

Anthony said the Heat tested his back, banging him around, pushing and holding during the game. Anthony indicated he’s not 100 percent healthy, but the high-scoring forward said he doesn’t ever expect to feel that way as long he’s in the league.

“As far as anything just lingering and affecting me today, I felt good for the most part,” Anthony said.

J.R. Smith (flu-like symptoms) didn’t practice after playing just six minutes in Sunday loss.

The enigmatic shooting guard came to the MSG Training Center Monday morning, but was sent home by team doctors because he was still sick. He is questionable for Tuesday’s game against the Nets, Knicks coach Derek Fisher said.

“Hopefully he will improve a lot over the next day or so with some rest and we will see where he is [on Tuesday],” Fisher said.

Fisher praised the play of Amar’e Stoudemire and the leadership he has demonstrated lately. Stoudemire, who questioned his team’s desire after an ugly blowout lost to the Thunder last week, backed up his big words on Sunday, logging a season-high 37 minutes and scoring 19 points to go along with 12 rebounds.

“I think he is doing a great job of being aggressive out there, taking his opportunities when they are there,” Fisher said of the injury-prone 32-year-old forward. “But I think he is also trying to utilize his voice and his presence on the team as a teammate to galvanize the guys and get everybody continuing to want to be on the same page.

“Amar’e is a guy who has been here long enough and hopefully guys respect him enough to hear what he’s saying.”

Fisher wouldn’t commit to continuing to play Stoudemire so many minutes. It was his first game of 30 or more.

“We have to make sure we still find ways to not do that too much so that he can remain healthy,” the first-year coach said.